At present, the silver salt diffusion transfer method is well known in the art and, as a result, a description thereof will be brief. The details thereof are described in A. Rott and E. Weyde, "Photographic Silver Halide Diffusion Processes", Focal Press Co. (1972); J. Sturge, V. Walworth and A. Shepp, "Imaging Processes and Materials: Neblette's Eighth Edition", Chapter 6, Instant Photography and Related Reprographic Processes, published by Van Nostrand Reinhold Co. (1989); and G. Haist, "Modern Photographic Processing Vol. 2", Chapter 8, Diffusion Transfer, John Wiley and Sons Co. Many kinds of photographic materials can be prepared by this diffusion transfer method, which are described in detail in the above publications. It is known, for example, that a light-sensitive element comprising a silver halide emulsion coated on a support and an image-receiving element containing silver precipitate nuclei are superposed and a processing element consisting of a high viscosity alkaline processing composition containing a developing agent and a silver halide solvent is spread between the above two elements, whereby a transferred image can be obtained.
In the above constitution, after the light-sensitive element is exposed, it is superposed on the image-receiving element and the processing element is spread therebetween and they are separated after a fixed time, whereby a transferred image can be obtained on the image-receiving element. It is always desired to complete the formation of this transferred image in less time.
Methods for accelerating the completion of the transferred image include a method in which a high reductive compound such as a hydroquinone is used as a developing agent and a solvent having a fast dissolving speed such as hypo is used as a silver halide solvent, and a method in which silver chloride and silver brmochloride each with a high solubility are used for a silver halide emulsion present in the light-sensitive element. In the former method, however, the transferred image is very instable and the image can not be stored for a long period of time because of the generation of stain by the oxidation product of a developing agent and the sulfurization by residual hypo present.
In order to prevent this, an anti-oxidation layer such as polyvinyl alcohol containing an alkaly neutralizing agent needs to be coated on the surface of the image immediately after completing the image, which complicates handling. The latter method has the disadvantage that it can not be used as a photograph because of low sensitivity and because the density of the transferred image is reduced since fog is tends to be formed.
Meanwhile, it is strongly desired for the fluctuation in the photographic properties to be small under various use conditions and particularly it is desired that the fluctuation due to temperature of use is small.
In the above two methods, temperature of use dependency tends to deteriorate.